In investigating all possible mitigation technologies, including those seemingly from the movies, scientists from the United States are looking at nuclear detonations to protect Earth from dangerous asteroids.
A team from Lawrence Livermore National Laboratory teamed up with a US Air Force technology team to test whether nuclear detonations are enough to deflect an Earth-threatening asteroid. CBS affiliate station KTVT first reported on the plan, with team member Lansing Horan IV explaining that the collaborative effort is looking to utilize neutron radiation from nuclear detonations to do the job.
"This means that a neutron yield can potentially heat greater amounts of asteroid surface material, and therefore be more effective for deflecting asteroids than an X-ray yield," Horan said. He adds that this neutron radiation is more penetrative compared to X-rays.
A report on the concept is presented as Horan's thesis, titled "Neutron Energy Effects on Asteroid Deflection," submitted to the Air Force Institute of Technology.
Protecting the Earth from Asteroids
Horan tells KTVT that there are "two basic options" in protecting Earth from threatening asteroids: disruption or deflection.
With disruption, excessive energy is sent to the asteroid, causing it to shatter into many fragments moving at extreme speeds. Basically, Earth's defense forces destroy the asteroid. Horan explains that previous works show that more than 99.5 percent of the original mass of the asteroid "would miss the Earth." However, he also notes that this option is more likely to be considered in the event of a relatively small asteroid or in cases where the "warning time" before impact.
On the other hand, deflection is considered a "gentler approach." Using a significantly smaller amount of energy, the approach redirects the asteroid, keeps it intact, and sends it into a slightly different trajectory with a different velocity.
Horan notes that over time, in the context of several years before impact, even the slightest change in velocity could spell the difference between an asteroid hit and miss. He adds that deflection is generally preferred, being the "safer and more elegant option," provided that there is enough warning time for this kind of response.
Pinpointing the Right Amount of Energy to Deflect Asteroids
The work between the US Air Force technologists and Lawrence Livermore National Laboratory researchers is a small step towards deflection simulations using nuclear detonations.
The Air Force Institute of Technology member explains that one ultimate goal is in determining the optimal neutron energy spectrum for use in the application. This refers to the range or spread of neutron energy outputs that will be deposited in the best possible way to create deflection or a change in the space object's velocity. This requires an emphasis on the precision and accuracy of the energy deposition data,
"If the energy deposition input is incorrect, we should not have much confidence in the asteroid deflection output," Horan summarizes. He explains that the importance of the energy deposition profile for asteroid deflection applications is the most important for achieving optimal yields, which is extremely critical for redirecting larger asteroids.
He additionally explains that a plan to mitigate a large incoming asteroid will require an energy deposition spatial profile to correctly model the projected velocity change in the object.
"It is important that we further research and understand all asteroid mitigation technologies in order to maximize the tools in our toolkit," Horan adds.
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